Deepwater containment system with surface separator and method of using same

ABSTRACT

A subsea oil containment system, comprising a subsea collector located near a bottom of a body of water; a surface collector located near a surface of the body of water; and a riser connected to the subsea collector at a first end and extending to a second end located near the surface collector.

This application claims the benefit of U.S. Provisional Application No. 61/376,534 filed Aug. 24, 2010, the entire disclosure of which is hereby incorporated by reference.

BACKGROUND

When oil and gas is spilled into the sea, for example from a leaking tanker ship, a leaking pipeline, from oil seeping from an underground formation, or from oil flowing from a subsea wellhead or blowout preventer, there is a desire to collect the oil and gas and contain and transport or otherwise dispose of the oil and gas to prevent environmental damage to the sea and nearby coastlines. Various systems and methods of collecting spilled oil and gas are known in the art and set forth below:

U.S. Pat. No. 4,405,258 discloses a method for storing a lighter-than-water fluid, e.g., oil, produced from the blowout of an offshore subsea well. The method includes the steps of deploying a containment dome in shallow water near the location of the seabed where the containment dome is to be located. The containment dome as an upper expanded dome-like fluid impervious membrane, a fluid impervious hollow peripheral ring attached to the periphery of the membrane to provide a depending bag-like container, and discrete water drainage means within the bag-like container for connection to pump conduit means therefrom. Wet sand from the seabed is then pumped into the bag- like container, and water is then drained from the wet sand through the water drainage means so as to provide a body of drained sand disposed within the bag-like container and providing a hollow peripheral ring as a hollow peripheral torus acting as a self-supporting structure and as an anchor for the dome-like structural unit. The dome is then charged with a buoyant amount of air and the buoyed dome is floated out to the site where the dome is to be deployed. It is then submerged by controllably releasing the air while substantially simultaneously filling the dome with water, thereby sinking the dome until the lighter-than- water fluid is captured within the dome, while such fluid substantially simultaneously displaces water from within the dome. U.S. Pat. No. 4,405,258 is herein incorporated by reference in its entirety.

U.S. Pat. No. 4,643,612 discloses an oil storage barge having a concave bottom is adapted to be anchored over a subsea well or pipeline that is leaking oil. Flexible skirts extend to the ocean floor, and oil that is trapped under the barge may be stored in the barge or then transferred to another vessel. U.S. Patent Number 4,643,612 is herein incorporated by reference in its entirety.

U.S. Pat. No. 5,114,273 discloses a protective device installed to or around an offshore drilling platform for oil or gas and the device when in operation to encircle or enclose the platform with a floating containment device and attached oil containment curtain hanging from the device to the ocean floor. The pollution containment device to be submerged normally and activated to the surface when needed. This device will entrap offshore platform pollutants in a short amount of time with a minimum amount of effort and will maintain a clean environment. Other methods of offshore platform pollution containment devices are shown, including permanent non-moving oil pollution containment barriers and activated barriers that operate internally and externally of the oil platform to form an all encompassing barrier from the ocean floor to above the water surface to hold an oil spill to the platform area. U.S. Pat. No. 5,114,273 is herein incorporated by reference in its entirety.

U.S. Pat. No. 5,213,444 discloses an oil/gas collector/separator for recovery of oil leaking, for example, from an offshore or underwater oil well. The separator is floated over the point of the leak and tethered in place so as to receive oil/gas floating, or forced under pressure, toward the water surface from either a broken or leaking oil well casing, line, or sunken ship. The separator is provided with a downwardly extending skirt to contain the oil/gas which floats or is forced upward into a dome wherein the gas is separated from the oil/water, with the gas being flared (burned) at the top of the dome, and the oil is separated from water and pumped to a point of use. Since the density of oil is less than that of water it can be easily separated from any water entering the dome. U.S. Pat. No. 5,213,444 is herein incorporated by reference in its entirety.

U.S. Pat. No. 6,592,299 discloses a method of detecting and locating fresh water springs at sea essentially by taking salinity measurements and by methods and installations for collecting the fresh water. The collection installations comprise an immersed bell-shaped reservoir containing and trapping the fresh water in its top portion, and a pumping system for taking fresh water and delivering the fresh water via a delivery pipe, characterized in that the circumference of the bottom end of the reservoir and/or the circumference of the bottom end of a chimney inside the reservoir and open at its top end and surrounding the fresh water resurgence in part and preferably in full, follow(s) closely the outline of the relief of the bottom of the sea so as to provide leakproofing between the circumference(s) and the bottom of the sea. U.S. Pat. No. 6,592,299 is herein incorporated by reference in its entirety.

There is a need in the art for one or more of the following:

Improved systems and methods for collecting spilled oil and gas from a marine environment;

Improved systems and methods for collecting oil and gas spilling from a subsea well;

Improved systems and methods for collecting oil and gas spilling from a subsurface formation located beneath a body of water; and/or

Improved systems and methods for collecting oil and gas spilling from a subsurface formation located beneath a body of water, and then burning the gas and containing the oil in a surface vessel.

SUMMARY OF THE INVENTION

One aspect of the invention provides a subsea oil containment system, comprising a subsea collector located near a bottom of a body of water; a surface collector located near a surface of the body of water; and a riser connected to the subsea collector at a first end and extending to a second end located near the surface collector.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the features and advantages of the present invention can be understood in detail, a more particular description of the invention may be had by reference to the embodiments thereof that are illustrated in the appended drawings. These drawings are used to illustrate only typical embodiments of this invention, and are not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale or in schematic in the interest of clarity and conciseness.

FIG. 1 is a schematic diagram depicting a wellsite positioned about a subsea reservoir, the wellsite having a containment system in accordance with an aspect of the present invention.

FIG. 2A is a schematic diagram depicting a wellsite positioned about a subsea reservoir, the wellsite having a containment system with a surface separator in accordance with an aspect of the present invention.

FIG. 2B is a schematic diagram depicting a wellsite positioned about a subsea reservoir, the wellsite having an alternate containment system with the surface separator of FIG. 2A.

FIG. 3 is a schematic diagram depicting a diffuser.

FIG. 4A is a schematic diagram depicting a barge with a rotary table extending therefrom. FIG. 4B is a schematic diagram depicting the barge of FIG. 4A with an alternate rotary table on a surface thereof.

FIG. 5 is a flow chart depicting a method of deepwater containment.

FIG. 6 is a schematic diagram depicting a wellsite positioned about a subsea reservoir, the wellsite having a containment system in accordance with an aspect of the present invention.

DETAILED DESCRIPTION

Presently preferred embodiments of the invention are shown in the above-identified figures and described in detail below. Embodiments are described with reference to certain features and techniques for containing fluids released into the sea.

FIG. 1:

FIG. 1 is a schematic diagram depicting a wellsite 100 positioned about a subsea reservoir 102. The wellsite 100 is provided with a containment system 101 for capturing fluids released into the sea 103. Preferably, the containment system 101 and each of its components are configured for operability in harsh conditions and/or are transportable as needed.

The wellsite 100 includes a surface collector 104 floating on the sea 103 or submerged a distance below a surface of the sea, for example from about 50 to about 200 meters. Collector 104 has a riser 106 extending below it for receiving fluids generated from the reservoir 102. A subsea end of the riser 106 is positioned above a blow out preventer (BOP) 112 positioned on the sea floor (or mud line) 110. The BOP 112 is positioned above a wellbore 114 that extends through the subsea floor 110 and into the reservoir 102. The BOP 112 is in fluid communication with the wellbore 114 for receiving the fluids (e.g., gas, hydrocarbons, water, etc.) from the reservoir 102.

The riser 106 may be, for example, a conventional riser or tubular member for allowing fluid to naturally flow from the BOP 112 to the surface. Fluid drawn from the reservoir 102 and to the surface via riser 106 may be stored in the surface collector 104. The surface collector 104 may be, for example, a separator that separates components of the fluid, such as gas and liquid, as will be described more fully herein.

In one embodiment, collector 104 may have a sealed top with an outlet connected to flare 124. In another embodiment, collector 104 may have an open top with an outlet to the air which allows gases and/or volatile compounds to escape into the atmosphere.

In one embodiment, collector 104 may have a sealed bottom with an inlet connected to riser 106. In another embodiment, collector 104 may have an open bottom with an inlet to the sea which serves to collect buoyant gases and/or liquids which are floating towards the surface of the sea.

Some portions of the fluid stored in the surface collector 104 may optionally be removed, for example, by burning the gas with a flare 124. The pressure of the fluid may be reduced in the surface collector 104. Other portions of the fluid may be passed to a vessel 120 via tubing (or hoses, floating line or off-take lines) 126 for transport. The tubing 126 fluidly connects the surface collector 104 to the vessel 120 for establishing fluid communication therebetween.

From time to time, fluid from the reservoir 102 may escape into the sea 103. In some cases, a leak 130 may allow fluid to escape from the wellsite system 100 and into the sea 103 as fluid is produced from the reservoir 102. In such cases, the containment system 101 may be employed to re-capture fluid released by one or more leaks 130.

As shown in FIG. 1, the subsea containment system 101 includes a subsea collector 132 positionable about the leak(s) 130. The subsea collector 132 may be fluidly connected to riser 106 for passing fluid thereto. The subsea collector 132 is configured to capture fluid released by leak 130, and to prevent release of reservoir fluids into the sea 103 as will be described more fully herein.

Collector 132 may be a direct flange connection to the BOP 112. Alternatively, collector 132 may be a containment cap sealed to the BOP 112 or sealed to the mudline 110 about the BOP 112. Alternatively, collector 132 may be a containment cap not sealed to the BOP 112, which may be open to the sea 103, and which may allow some seawater to flow into the collector 132 and may allow some fluid from leak 130 to flow out of collector.

FIGS. 2A & 2B:

FIGS. 2A and 2B are schematic diagrams depicting a wellsite 200 having a containment system 201 a,b, respectively. The containment systems 201 a,b are each provided with a subsea collector 232, a riser 206, and a surface collector 204 a,b that may operate in the same manner as the collector 132, the riser 106, and the surface collector 104, respectively, of FIG. 1. BOP 212 may also be provided for passing fluid from a reservoir via a wellbore in the same manner as the BOP 112 of FIG. 1.

Referring first to the containment system 201 a of FIG. 2A, the subsea collector 232 is positioned over BOP 212 such that a leak 230 from BOP 212 may be collected therein. Fluid passing from the BOP 212 into the subsea collector 232 passes into the riser 206. In some aspects, a conventional collector may be used to capture fluid from the leak 230 from the BOP 212 and prevent the leak 230 from releasing into the sea 203. Alternatively, the subsea collector 232 may have a dome configuration for capturing fluid.

The subsea collector 232 is secured at a bottom end of the riser 206 by a riser coupler 234, and is in fluid communication therewith. The subsea collector 232 may be tethered to sea floor 210 by clump weights 254, by driven piles, or by suction piles, or other anchoring systems as are known in the art. Preferably, the subsea collector 232 is secured into position using multiple (e.g., about four) weights of about ten thousand kilograms each positioned about the subsea collector 232. The subsea collector 232 may be secured at about 3 to about 15 meters above the sea floor 210, depending on the height of BOP 212.

The subsea collector 232 may have a dome-shaped or open bottom configuration. The subsea collector 232 is positioned over the BOP 212 to capture the fluids released by the leak 230. The subsea collector 232 has a cylindrical portion 236 extending from an open bottom 238 to a tapered portion 240. The tapered portion 240 has an open end 242 that terminates at the riser coupler 234. The frusto-conical shape of the subsea collector 232 preferably facilitates the flow of the fluid from the leak into the riser 206. The cylindrical portion 236 and tapered portions 232 may have, for example, a height of about 3 to about 5 meters each.

Subsea collector 232 may be made of a metal such as steel or aluminum, a polymer, and may optionally be coated with an insulated material, such as syntactic foam insulation (e.g., having about 5 to about 15 cm thickness). The insulation preferably makes the seabed collector 232 near neutral in water to minimize buoyancy needs.

The riser 206 extends from the subsea collector 232 to the surface collector 204 a for passing fluid therebetween. The riser 206 may be a free standing, buoyed and insulated riser. The riser 206 may be made of a metal such as steel or aluminum, or a polymer, and may optionally be coated with an insulated material for example, a low density syntactic foam. The riser 206 may be filled with diesel during startup to provide buoyancy in water to start up flow and/or to prevent hydrate formation. The riser 206 comprises riser tubes 244 a,b, valves 246 a,b, buoyant section 248 and diffuser 250. The riser tubes 244 a,b may be, for example, about 30 cm to about 60 cm diameter risers. One or more riser tubes 244 a,b may be provided in riser 206 for passing fluid therethrough. The tubes 244 a,b may be of the same or different dimensions.

One or more valves (e.g., restrictor valves) 246 a,b on the riser 206 may be provided for controlling the flow of fluid through the riser 206. The valves 246 a,b may be used to control pressure ranges and to monitor potential conditions, such as riser collapse or burst. Preferably, the valves 246 a,b may be opened gradually, and maintained with at least some flow at all times to prevent hydrates from forming in the subsea collector. The valves 246 a,b may be remotely actuated vehicle valves that are selectively activated by an ROV 252 deployed from vessel 220 via an umbilical 255, or from another vessel (not shown). While only one vessel 220 with one ROV 252 is depicted, one or more vessels 220 and/or ROVs 252 may be provided. A hot stab 256 may be provided about the riser 206 for receiving the ROV 252 and enabling activation thereof. The riser 206 may also optionally be provided with devices, such as clean out ports, chokes (not shown) or other devices as desired.

One or more buoyant portions 248 may be positioned about riser 206 for providing buoyant support thereto. The buoyant portion 248 may be a tubular member with buoyant material for providing buoyancy. Alternatively, the buoyant portion 248 may be a buoyant material positioned about a tube, such as riser tube 244 b, for providing buoyant support thereto. Buoyancy may be provided about various positions of the riser 206. Preferably, the buoyant portion(s) 248 are adjustably positionable about the riser 206 and/or other components of the containment system 201 a.

The diffuser 250 may be positioned at a surface end of the riser 206 for distributing at least a portion of the fluid as it is released from the riser 206 into the surface collector 204 a. Preferably, the diffuser reduces pressure and/or velocity of the fluid passing from the riser 206 and into the surface collector 204 a. The diffuser 250 is preferably a distance below collector 204 a (e.g., about thirty to fifty meters below collector). The diffuser 250 has a plurality of diffuser tubes 258 extending therefrom for providing multiple paths for releasing fluid from the riser 206 into the surface collector 204 a. The diffuser tubes 258 each have diffuser outlets 260 that may be aimed in different directions to facilitate flow from each of the diffuser tubes 258 and into the surface collector 204 a. The riser 206 may extend through the diffuser 250 for releasing a portion directly therefrom. Alternatively, the riser 206 may divert some or all of the fluid therein through the diffuser tubes 258.

Surface collector 204 a receives the fluid released from diffuser 250 and/or riser 206. As shown in FIG. 2A, the surface collector 204 a is a cylindrically-shaped member having an open bottom and open top in a ‘donut’ or ‘ring’ configuration (but may be of any shape for collection and/or separation as desired). The surface collector 204 a may be configured to facilitate receipt, separation and/or transfer of the fluids generated from the leak 230. The surface collector 204 a is preferably a gravitational separator capable of separating the fluid into, for example, gas and liquids. As shown in FIG. 2A, the fluid may be separated, for example, into portions containing oil 278 and water 280, with a gas portion (not shown) released into the air.

A flagpole (or flexible joint) 270 a is positionable at a surface end of the riser 206 for providing support thereto. The flagpole 270 a has a spindle 271 connected at an upper end of the riser 206. An internal blockhead plate 276 may be provided between the flagpole 270 a and the riser 206 for providing separation therebetween. The flagpole 270 a preferably has flags 272 extending from to the spindle 271. The flagpole 270 a preferably has sufficient flags 272 positionable in the fluid in the surface collector to stabilize a surface end of the riser 206.

The surface collector 204 a (as well as other portions of the containment system 201 a) may be provided with various other devices, such as gauges, chokes, valves (e.g., ballast valves), pumps, flares, or other devices for manipulating capture and/or transport of the fluid. For example, a gauge 282, such as a simple or floating level gauge, may be provided in collector 204 a for monitoring fluid levels (e.g., oil levels). The surface collector 204 a may also depicted as having various flowlines, valving or ports for passing fluids thereto and therefrom. Surface collector 204 a may have a dynamic positioning system, one or more mooring lines, or may be attached to one or more vessels for station keeping.

Fluid may be pumped into the collector 204 a via pump supply or flow line 284 and/or released via exhaust 286. The pump supply line 284 and exhaust 286 may be connected to a pump 288 for operation therewith. The pump 288 may be used to selectively pump pressure into the collector 204 a. The pump 288 may also be used to pump portions of the collected fluids, such as oil 278, from the separator 204 a to a vessel 220. The pump 288 may be integral with the surface collector 204 a, or separate therefrom. The pump 288 may be hydraulically powered by sea water, with no return, or by hydraulic fluid with return to the tanker.

An outlet port 290 may also be provided for receiving transfer hose 292. The transfer hose 292 is preferably a floating hose for establishing fluid communication between the surface collector 204 a and a vessel 220. The fluid in the collector 204 a may be passed via the transfer hose 292 to vessel 220 for transport. One or more pumps, supply lines, exhausts, tubings, ports and/or other devices may be provided to generate the desired offloading rate. Also, one or more vessels may be used in series and/or parallel.

Referring now to the containment system 201 b of FIG. 2B, the containment system 201 b is the same as the containment system 201 a, except that the collector 204 a has been replaced with a modified collector 204 b with a closed top with a flare 224, and the flagpole 270 a has been replaced with a tether connector (or flexible joint) 270 b. While FIGS. 2A and 2B are shown with specific versions of the collector 204 a,b, flagpole 270 a and/or tether connector 270 b, it will be appreciated by one of skill in the art that the selected configuration may have various combinations of these components.

The surface collector 204 b is similar to the collector 204 a, except that the collector 204 b has a closed top 273. The surface collector 204 b may be pressurized for maintaining the fluid collected therein at a desired pressure, or collector 204 b may be attained at ambient pressure. This dome or closed-top configuration prevents the release of gas from the surface collector 204 b. In such cases, a flare 224 may be provided to burn off portions of the liquid, such as oil or gas. Alternatively, the gas may also be released from the surface collector 204 b with the fluid transferred via 245 to the vessel. The fluid level gauge 282 may extend through the closed top 273.

Although surface collector 204 b is shown floating on or slightly above the surface of the water in the Figure, in another embodiment, surface collector 204 b with a top 273 may be submerged at a depth from about 10 meters to about 100 meters, or from about 20 meters to about 50 meters.

Tether connector (flexible joint) 270 b is a flexible interface between the riser 206 and the surface collector 204 b to act as a flexible joint therebetween. The tether connector 270 b comprises an anchor tube 275 connected to a surface end of the riser 206 adjacent the internal blockhead plate 233. Preferably, the tether connector 270 b provides a flexible connection between the riser 206 and the surface collector 204 b for flexible movement therebetween, for example, to absorb movement due to waves and/or current. The anchor tube 275 has riser anchors 277 extending therefrom. Collector anchors 279 are positioned about the surface collector 204 b, preferably at a bottom thereof. Tethers 281 extend from the riser anchors to the collector anchors 279 for securing the surface collector 204 a about the riser 206. While two riser anchors 277, collector anchors 279 and tethers 281 are shown, it will be appreciated that any number of such components may be provided as needed to support the collector 204 a in position about the riser 206, for example from about 2 to 6, or from about 3 to 4. Also, as shown in FIG. 2B, the tethers 281 may be anchored to diffuser 350 via riser anchors 277 positioned thereon.

While FIGS. 2A and 2B depict certain flexible joints 270 a,b forming a flexible interface between the riser 206 and the surface collector 204 b, the flexible joint may be any flexible interface, such as elastomeric elements or other flexible joints between the riser 206 and the surface collector 204 b. For example, a compliant ring may be provided about the collector 204 b through which a flagpole (e.g., 270 a) may be stabbed. A connector may be positioned at a base of the flagpole, preferably about 20-30 feet (m) below the interface. Optionally, the flagpole may be eliminated and the compliant ring may be positioned about the riser 206.

FIG. 3:

FIG. 3 is a detailed view of a diffuser 350 that may be used as the diffuser 250 of FIGS. 2A and 2B. In this configuration, the diffuser 350 has a first tubular portion 362, a rib portion 364 and a second tubular portion 366. The first tubular portion 362 extends from the riser 306 and is supported therein. The rib portion 364 extends between the first tubular portion 362 and second tubular portion 366 for providing fluid communication therebetween for passage of fluid from the riser 206 therethrough. The rib portion 364 has ribs 368 for receiving the diffuser tubes 258 of FIGS. 2A and 2B and releasing fluid therethrough. The second tubular portion 366 is connectable to the surface collectors 204 a,b of FIGS. 2A and 2B as will be described further herein. Riser anchors 277 for supporting tethers 281 may be provided as will be described more fully herein.

FIGS. 4A & 4B:

FIGS. 4A and 4B depict vessels 420 a,b usable as the vessel 120 and/or 220 of FIGS. 1-2B. The vessels 420 a,b may be used for deploying one or more components of the containment system(s) 201 a,b. The vessels 420 a,b may be purpose built or dedicated barges deployable to the wellsite 200 for operation therewith. Each of the vessels (or barges) 420 a,b has a crane 455 with a boom 457 extending therefrom, a rack of pipe joints 459, a funnel 461, and power tongs 463 for makeup. The crane 455 may be a 100 metric ton crane with casing elevators (not shown). The crane 455 and boom 457 are configured for installation of the components of the containment system(s) 201 a,b.

The vessel 420 a,b may be, for example, a 15 m by 50 m barge for transporting equipment and fluids. As shown in FIG. 4A, the vessel 420 a is barge provided with a false rotary table 465 a extending therefrom and provided with railings 467 thereabout. As shown in FIG. 4B, the vessel 420 b is a barge provided with a false rotary table 465 b positioned on a surface of the barge.

FIG. 5:

FIG. 5 is a flow chart depicting a method 500 of containment. The method 500 may involve transporting 583 the containment system to a BOP at a wellsite. The transporting may involve deploying at least a portion of the containment system (e.g., 101, 201 a,b) to a wellsite, installing the containment system (e.g., 101, 201 a,b) about a BOP (e.g., 112, 212), and removing the containment system. During removal, it may be necessary to remove the surface collector by deblasting, disconnecting and towing to a desired location. Optionally, the riser 206 may remain in position downhole while the surface collector (e.g., 104, 204) is temporarily removed for bad weather.

The method may also involve collecting 585 a fluid leaking from a BOP (e.g., 112, 212) in a subsea collector (e.g., 232) positioned thereabout, passing 587 the fluid from the BOP (e.g., 112, 212) to a riser (e.g., 106, 206) via the subsea collector (e.g., 232) and passing 589 at least a portion of the fluid from the riser to a surface collector (e.g., 204 a,b). The method may further involve diffusing 591 with a diffuser (e.g., 250) at least a portion of the fluid passing from the riser to the surface collector (e.g., 204 a,b), storing 593 the fluid in the surface collector (e.g., 204 a,b), and separating 594 the fluid in the surface collector (e.g., 204 a,b).

In some cases, the method may involve burning 595 at least a portion of the fluid in the surface collector (e.g., 204 a,b), and transferring 596 at least a portion of the fluid from the surface collector (e.g., 204 a,b) to at least one vessel (e.g., 120, 220). In some cases, the riser (e.g., 106, 206) may be secured 598 to the surface collector (e.g., 204 a,b) with a flexible joint (e.g., 270 a,b). The riser (e.g., 106, 206) may be secured 599 about the BOP (e.g., 112, 212) with weights (e.g., 254). An ROV vessel (e.g., 120, 220) may be provided for deploying 597 an ROV (e.g., 252) from the ROV vessel to the wellsite for activation thereof. The steps of the method may be performed in any order, and repeated as desired.

FIG. 6:

FIG. 6 is a schematic diagram depicting a wellsite 600 positioned about a subsea reservoir 602. The wellsite 600 is provided with a containment system 601 for capturing fluids released into the sea 603. Preferably, the containment system 601 and each of its components are configured for operability in harsh conditions and/or are transportable as needed.

The wellsite 600 includes a surface collector 604 floating on the sea 603 or submerged a distance below a surface of the sea, for example from about 0 to about 50 meters. Collector 604 has a riser 606 below it for receiving fluids generated from the reservoir 602. A subsea end of the riser 606 is positioned above a blow out preventer (BOP) 612 positioned on the sea floor (or mud line) 610. The BOP 612 is positioned above a wellbore 614 that extends through the subsea floor 610 and into the reservoir 602. The BOP 612 is in fluid communication with the wellbore 614 for receiving the fluids (e.g., gas, hydrocarbons, water, etc.) from the reservoir 602.

The riser 606 may be, for example, a conventional riser or tubular member for allowing fluid to naturally flow from the BOP 612 to the surface. Riser 606 includes first portion 606 a which may be neutrally buoyant and extends to within about 50 m to 200 m of sea level 660. Riser 606 also includes second portion 606 b which may be buoyant and extends above first portion 606 a, for example from a depth of about 50 m to 200 m, to within about 10 m to 100 m of sea level 660. An ROV actuated valve 634 may be provided between first portion 606 a and second portion 606 b. A block valve 638 may be provided at a top end of second portion 606 b, with a diesel injection port 636 located just below block valve 638.

Fluid drawn from the reservoir 602 and to the surface via riser 606 may be stored in the surface collector 604. The surface collector 604 may be, for example, a separator that separates components of the fluid, such as gas and liquid, as will be described more fully herein.

In one embodiment, collector 604 may have a sealed top with an outlet connected to flare 624. In another embodiment, collector 604 may have an open top with an outlet to the air which allows gases and/or volatile compounds to escape into the atmosphere.

In one embodiment, collector 604 may have an open bottom with an inlet to the sea which serves to collect buoyant gases and/or liquids which are floating towards the surface of the sea from riser 606.

Some portions of the fluid stored in the surface collector 604 may optionally be removed, for example, by burning the gas with a flare 624. The pressure of the fluid may be reduced in the surface collector 604. Other portions of the fluid may be passed to a vessel 620 via tubing (or hoses, floating line or off-take lines) 626 for transport, for example with pump 625. The tubing 626 fluidly connects the surface collector 604 to the vessel 620 for establishing fluid communication therebetween.

From time to time, fluid from the reservoir 602 may escape into the sea 603. In some cases, a leak 630 may allow fluid to escape from the wellsite system 600 and into the sea 603 as fluid is produced from the reservoir 602. In such cases, the containment system 601 may be employed to re-capture fluid released by one or more leaks 630.

As shown in FIG. 6, the subsea containment system 601 includes a subsea collector 632 positionable about the leak(s) 630. The subsea collector 632 may be fluidly connected to riser 606 for passing fluid thereto. The subsea collector 632 is configured to capture fluid released by leak 630, and to prevent release of reservoir fluids into the sea 603 as will be described more fully herein.

Collector 632 may be a direct flange connection to the BOP 612. Alternatively, collector 632 may be a containment cap sealed to the BOP 612 or sealed to the mudline 610 about the BOP 612. Alternatively, collector 632 may be a containment cap not sealed to the BOP 612, which may be open to the sea 603, and which may allow some seawater to flow into the collector 632 and may allow some fluid from leak 630 to flow out of collector.

In some embodiments, collector 632 may be a flange which is directly bolted and/or sealed to BOP 612.

In some embodiments, collector 632 may be a dome which is cemented in place around BOP 612.

In some embodiments, collector 632 may be a dome which is sealed around the BOP 612, and anchored to and sealed to the sea floor 610 with annular suction piles.

In some embodiments, collector 632 may be a dome which is sealed around the BOP 612, by forcing the edges of the dome down into the sea floor 610.

In some embodiments, collector 632 may be a dome which is not sealed around the BOP 612, and which provides one or more areas of access between the BOP 612 and the body of water 603.

In some embodiments, riser 606 may be connected directly to and located directly above collector 632.

In some embodiments, collector 604 may be a truss structure 640 having a circular or donut shape with an opening in the interior to contain fluids, and a skin 642 about the exterior for containing the fluids within collector 604. Truss 640 may be constructed of steel I-beams or other structural members as are known in the art and provided with buoyancy (not shown). Skin 642 may be a flexible impermeable fabric or polymer material.

Collector 604 may be kept on station with one or more thrusters, anchoring devices, or by cables connected to one or more vessels, for example 3 vessels, that pull collector 604 into the desired location.

Suction piles 632 may be provided to anchor collector 630 and/or riser 606 to sea floor 610.

Illustrative Embodiments

In one embodiment, there is disclosed a subsea oil containment system, comprising a subsea collector located near a bottom of a body of water; a surface collector located near a surface of the body of water; and a riser connected to the subsea collector at a first end and extending to a second end located near the surface collector. In some embodiments, the subsea collector comprises a containment cap located over a source of oil located on the bottom of the body of water. In some embodiments, the subsea collector comprises a containment cap sealed to a blow out preventer (BOP) located on the bottom of the body of water. In some embodiments, the subsea collector is anchored to the bottom of the body of water with one or more clump weights and/or piles. In some embodiments, the system also includes a diffuser connected to the second end of the riser. In some embodiments, the surface collector comprises a sealed bottom surface, the sealed bottom surface connected to the second end of the riser. In some embodiments, the surface collector comprises an open bottom surface, the open bottom surface located above the second end of the riser. In some embodiments, the surface collector comprises a sealed top surface, the surface collector comprising a first outlet for gases near a top of the collector, and comprising a second outlet for liquids near a bottom of the collector. In some embodiments, the surface collector comprises a sealed top surface, the surface collector comprising a first outlet for gases near a top of the collector, and comprising a flare connected to the first outlet. In some embodiments, the surface collector comprises a sealed top surface, wherein the top surface of the surface collector is submerged in the body of water at a depth from about 20 to about 60 meters. In some embodiments, the surface collector comprises an open top surface, wherein the open top surface comprises a first outlet for gases, and comprising a second outlet for liquids near a bottom of the collector. In some embodiments, the system also includes a vessel fluidly connected to the surface collector by a hose, the vessel adapted to store and/or transport at least a portion of liquids in the surface collector. In some embodiments, the surface collector further comprising a pump connected to the hose. In some embodiments, the system also includes one or more tethers connecting the second end of the riser to the surface collector.

In one embodiment, there is disclosed an oil and gas collection system, comprising a source of oil and gas flowing into a body of water; a collector located adjacent the source of oil and gas; a riser to transport the oil and gas towards a surface of the body of water, a first end of the riser fluidly connected to the collector; and a separator floating on a surface of the body of water and located near a second end of the riser, the separator adapted to separate the oil and gas into a first oil rich stream and a second gas rich stream, the separator comprising an oil rich stream outlet and a gas rich stream outlet. In some embodiments, the source of oil and gas comprises a blow out preventer. In some embodiments, the collector is sealed to the source of oil and gas. In some embodiments, the collector is open to the source of oil and gas and the body of water. In some embodiments, the collector comprises a containment dome. In some embodiments, the riser is anchored to a sea floor beneath the body of water. In some embodiments, the riser is anchored to a sea floor with a suction pile driven into the sea floor. In some embodiments, the system also includes a manifold located between the collector and the riser. In some embodiments, the system also includes a plurality of hoses connected the manifold with the first end of the riser, where the manifold may include a valve connected to each of the hoses. In some embodiments, the system also includes a pump with an outlet feeding into the first end of the riser. In some embodiments, the separator is floating on a surface of the body of water. In some embodiments, the separator is operating at a pressure from about 5 to about 50 psi. In some embodiments, the system also includes a flare at a surface of the body of water, the flare fluidly connected the gas rich stream outlet. In some embodiments, the system also includes a trap at a first end of the riser, the trap comprising an access port for cleaning out the trap. In some embodiments, the system also includes a vessel floating on a surface of the body of water, the vessel fluidly connected to the oil rich stream outlet. In some embodiments, the oil rich stream comprises a portion of gas, the vessel further comprising a separator to separate the portion of gas from the oil. In some embodiments, the separator on the vessel is a low pressure separator, for example operating a pressure less than about 25 psi. In some embodiments, the vessel further comprises a flare adapted to burn the portion of gas.

In one embodiment, there is disclosed a method comprising locating a source of oil and gas flowing into a body of water; collecting at least a portion of the oil and gas; flowing the collected oil and gas to a surface of the body of water; separating at least a portion of the oil from the gas; flowing the portion of oil to a floating vessel; and burning at least a portion of the gas.

It will be understood from the foregoing description that various modifications and changes may be made in the preferred and alternative embodiments of the present invention without departing from its true spirit. For example, one or more wellsites and/or components thereof (e.g., collectors, vessels, BOPS, risers, etc.) may be positioned about the reservoir for producing fluids and/or containing leaks.

This description is intended for purposes of illustration only and should not be construed in a limiting sense. The scope of this invention should be determined only by the language of the claims that follow. The term “comprising” within the claims is intended to mean “including at least” such that the recited listing of elements in a claim are an open group. “A,” “an” and other singular terms are intended to include the plural forms thereof unless specifically excluded. 

1. A subsea oil containment system, comprising: a subsea collector located near a bottom of a body of water; a surface collector located near a surface of the body of water; and a riser connected to the subsea collector at a first end and extending to a second end located near the surface collector.
 2. The system of claim 1, wherein the subsea collector comprises a containment cap located over a source of oil located on the bottom of the body of water.
 3. The system of claim 1, wherein the subsea collector comprises a containment cap sealed to a blow out preventer (BOP) located on the bottom of the body of water.
 4. The system of claim 1, wherein the subsea collector is anchored to the bottom of the body of water with one or more clump weights and/or piles.
 5. The system of claim 1, further comprising a diffuser connected to the second end of the riser.
 6. The system of claim 1, wherein the surface collector comprises a sealed bottom surface, the sealed bottom surface connected to the second end of the riser.
 7. The system of claim 1, wherein the surface collector comprises an open bottom surface, the open bottom surface located above the second end of the riser.
 8. The system of claim 1, wherein the surface collector comprises a sealed top surface, the surface collector comprising a first outlet for gases near a top of the collector, and comprising a second outlet for liquids near a bottom of the collector.
 9. The system of claim 1, wherein the surface collector comprises a sealed top surface, the surface collector comprising a first outlet for gases near a top of the collector, and comprising a flare connected to the first outlet.
 10. The system of claim 1, wherein the surface collector comprises a sealed top surface, wherein the top surface of the surface collector is submerged in the body of water at a depth from about 20 to about 60 meters.
 11. The system of claim 1, wherein the surface collector comprises an open top surface, wherein the open top surface comprises a first outlet for gases, and comprising a second outlet for liquids near a bottom of the collector.
 12. The system of claim 1, further comprising a vessel fluidly connected to the surface collector by a hose, the vessel adapted to store and/or transport at least a portion of liquids in the surface collector.
 13. The system of claim 12, the surface collector further comprising a pump connected to the hose.
 14. The system of claim 1, further comprising one or more tethers connecting the second end of the riser to the surface collector. 